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Standard eight Geography chapter 11. Man and Natural Environment. Hello friends. Welcome to sunday Remedios virtual classroom for Geography. This is the chapter Man and Natural Environment. In this chapter, we are going to learn about environment. What does environment mean? It is the surrounding conditions that affect the lifestyle of living things. Human life also gets affected by the environment. It includes biotic that is living and a biotic that is non living components and all the forms of energy it includes not only natural things, but also man made things. The environment influences the life of the people. Therefore we find human life to be different in different regions. For example, people living in forests have a completely different lifestyle compared to the life of the people who live in cities, concrete jungle. The former lives with more of natural environment and the latter lives in a more of a man made environment. What is natural environment? It consists of all the components which come into existence naturally. For example, landforms on the earth, the climate, water, minerals, soils, sunlight, plants and animals. They all affect the living world directly or indirectly cultural environment. In order to enrich his life, man uses the natural resources and brings about a change in the natural environment. For example, human settlement, roads, farmlands, dams, etcetera. Cultural environment is also called man made environment interaction in the environment. A number of interactions take place between the biotic and a biotic components. All biotic components depend on one another as well as a biotic components. For example, men breathe in and breathe out air plants use solar energy to produce food through photosynthesis ecology. It is a branch of science that studies the interrelationships, interdependence and interactions of the living things with their environment, ecosystem a biotic community that is closely interrelated and that interacts with the A biotic components is called an ecosystem. In an ecosystem. There is a close relationship between biotic and a biotic components. The entire earth is a huge ecosystem. Examples are aquatic ecosystem, forest ecosystem, meadow ecosystem, lake ecosystem bond ecosystem, desert ecosystem, etcetera. In an ecosystem we group the biotic components into three categories producers. That is all forms of vegetation consumers, that is primary consumers called herbivores, secondary and tertiary consumers called carnivores and D composers like microorganisms functions of the ecosystem. In an ecosystem, the main source of energy is the sun. With the help of the solar energy plants prepare their own food through the process of photosynthesis. Plants depend on the a biotic factors like sun, carbon dioxide, water and nutrients present in the soil for their growth. So plants are termed as producers or autotrophs. A part of the food produced is used by the plants for their growth and the rest is stored in the form of energy. These plants are used by herbivorous animals as food and animals get this organic energy stored by plants. Herbivores become food for carnivores and for omnivores like men. The energy that herbivores or carnivores receive is used to do their work. This is how the ecosystem functions. Let's take one example. The diagram shows, it's a grassland ecosystem where plants that is grass are the producers. Plants are eaten by hair, so the hair is called a primary consumer. The hair is eaten by a snake, hence the snake is called a secondary consumer. The snake becomes food for an eagle, so the eagle becomes a tertiary consumer, hens. The eagle becomes the highest level of consumer in the food chain, worms, insects, bacteria, fungi, molds, etcetera are called the composers. They decompose the organic matter like leaves, dead animals, dead birds, et cetera, into inorganic matter, which gets mixed with the soil. This soil in which in organic matter gets mixed becomes fertile and the plants get their nutrients from it. Energy transfer food chin. Solar energy is absorbed by the plants to prepare their food. This food stored in plants is energy. This energy gets transferred from primary, secondary and tertiary consumers to decompose us and finally returns to the environment. This completes the energy cycle. As energy gets transferred in the form of food, it is termed as the food chain and levels of food transfer are called trophic levels. Food web. A consumer can obtain his food in different ways. For example, in grassland ecosystem, a snake may opt in food from a hair or a mouse or a frog. As a result, many food chains exist in a single ecosystem. These chains are interconnected and this interconnection is called a food web. The food web shown is the soil where biotic waste is a food for bacteria, worms, moles, earthworm etcetera, moles are food for beetle and a dung beetle or a fly is food for worms and so on. Food pyramid. When energy is transferred from one trophic level to another, a part of it is lost either for the growth or for other activities of an organism. Therefore the energy in each trophic level decreases. If we try to represent the energy flow diagram, attic lee, it appears like a pyramid. It is called food pyramid, for example, the diagram of food pyramid shows 10,000 kilocalories at producer level, which becomes 1000 kilocalories at primary consumer level, 100 kilocalories at secondary consumer level, and finally 10 kg calories at the tertiary consumer level. If due to some reason the quantity of biomass increases or decreases it affects the other organisms in the trophic level environmental balance. So in this chapter what do we understand? A proper proportion of organisms and biomass in each trophic level helps the environment to be in balance. But due to natural hazards or human intervention, this balance in nature can be lost. Man with his intelligence, creativity and skill has developed a lot with the help of science and technology and has created a cultural environment of his own. But in the bargain man has cleared large stretches of forest lands and disrupted the smooth functioning of the environment. If man has a right to make use of the resources available in the nature to satisfy his needs, it becomes his duty to safeguard and protect the environment. So until next time all of you keep up the practice and all the best. We will proceed with the question and answer for the chapter for the revision of the chapter. There is also a mind map, which follows after the question answers. The mind map will help you revise the whole chapter quickly after you have gone through the mind map. Please note it down in your notebook.